The present invention is concerned with bearing assemblies, and in particular with a bearing retainer for retaining a bearing assembly in a housing, particularly for a bearing assembly in a Wind Turbine Generator.
A bearing needs is fitted with a shaft and housing and will have some level of clearance. To remove this internal clearance and create an interference fit, a preload is necessary. The preload is a permanent thrust load is applied to the bearing, and is applied to push the bearing so that it is. Any force that is applied to the shaft is known as preload.
A large majority of bearing failures on wind turbine generator high speed shafts are due to incorrect setting of the bearing. This is due to the design requirements of the gearbox, and the requirement for both accurate measurements of the gearbox and bearing, and the subsequent accurate manufacture of the bearing retainer. In addition, it is difficult to control preload/clearance without the requirement for ambiguous measurements to be taken, or accurate machining exercises.
In order to provide the correct preload/clearance for the bearing, it is required that the bearing retainer be fitted and manufactured specifically for each individual gearbox. These dimensional requirements are difficult to achieve during manufacture and are often impossible to achieve during maintenance, such as for example a nacelle re-work, despite diligent work. The resulting installed bearing therefore has an undetermined preload/clearance and therefore an undetermined life.
There is thus a need for a bearing retainer that can be applied to all gearboxes, of any manufacturer, which can be incorporated into any gearbox during a bearing replacement exercise, and which permits easy preload/clearance changes during the life of the bearing.
Brief Summary of the Invention
According to a first aspect of the invention, there is provided bearing arrangement comprising: a housing; a rotating member traversing the housing; a bearing assembly located between the housing and the rotating member; a retainer in contact with the housing and the bearing assembly, the retainer comprising positioning means adapted to engage with the housing. This means that the retainer is moveable to a predetermined position to retain the bearing assembly. This means that the retainer is moveable to a predetermined position, wherein a preload/clearance is applied to the bearing assembly. The bearing assembly is located in the bearing housing between a rotating member and the main housing, and the retainer comprises sealing means adapted to engage with the rotating member. This means that the retainer is able to form a seal with the rotating member. The retainer comprises a ring-shaped part which has on an outer surface a screw thread configured to engage with a screw thread on the housing. An inner surface of the ring shaped part comprises a seal member configured to seal against the rotating member. The housing includes a cover plate configured to engage with the retainer.
According to a further aspect of the invention, there is provided a method for maintaining a bearing comprising the steps of: disengaging the retainer from the housing; replacing the bearing assembly; engaging the retainer with the housing; and moving the retainer to a predetermined position to retain the bearing assembly.
According to a further aspect of the invention, there is provided a retainer for a bearing assembly, in which the bearing assembly is located in a housing, the retainer comprising: positioning means adapted to engage with the housing. This means that the retainer is moveable to a predetermined position to retain the bearing assembly. The retainer is moveable to a predetermined position to apply a preload or a clearance to the bearing assembly. The retainer comprises a ring-shaped part which has on an outer surface a screw thread configured to engage with a screw thread on the housing. An inner surface of the ring shaped part comprises a seal member configured to seal against the rotating member.
According to further aspects of the invention, there is provided a gearbox comprising the bearing arrangement or the retainer disclosed above and a wind turbine comprising the bearing arrangement or the retainer disclosed above.